1. Field of the Invention
The present invention relates to improvements in the manufacture of plastic bags in which a closure element is extruded from, or a zipper is attached to, the thermoplastic film used to make a reclosable bag. More specifically, the present invention relates to a method of applying or extruding an area of material on a wall of the bag opposite to and aligned with the closure element or zipper or applying the area of material to the zipper itself. This backing area of material has physical characteristics dissimilar to the material used to make the walls of the reclosable bag, thereby providing a difference in tactile feel to the user between the backing area and the remaining area of the walls of the bag.
2. Description of the Prior Art
The present invention relates to improvements in the package-making art and may be practiced in the manufacture of reclosable bags and packages of the kind that may be used for various consumer products. Such packages are often formed of a flexible plastic film and include a form of peel-seal to render the pack moisture-tight and/or airtight prior to an initial opening of the package. A zipper with interlocking profiles protects any remainder of the product therein after the initial opening. The interlocking profiles of the zipper may be integral with the package, or the interlocking profiles may be part of separate fastener strips attached to the film of the package.
In either instance, the interlocking profiles are typically interlocked during manufacture for convenience of storage and handling. However, difficulties are sometimes encountered by a user when the package is opened and closed because it is difficult to feel the interlocking profiles on the outer walls of the package.
In the prior art, the Tilman reference (U.S. Pat. No. 4,822,539) discloses the extrusion of the film and a male profile of the zipper used to make a reclosable bag. A reinforcing ridge is provided on the outer surface or outer walls of the bag film with the reinforcing ridge in alignment with the zipper. The reinforcing ridge reduces migration of the stabilizing ribs of the zipper; however, the reinforcing ridge also facilitates locating the zipper on the outer walls of the bag.
In the Ausnit reference (U.S. Pat. No. 4,479,244) the outer walls of a reclosable bag include vertical ridges as a frictional surface aligned with the closure element. The vertical ridges allow the closure element to be opened in various directions; however, the ridges also facilitate locating the closure element on the outer walls of the bag.
As described above, the prior art for locating and thereby facilitating the closure of zippers with interlocking profiles is fairly well developed but nevertheless remains open to improvements, specifically those improvements which provide alternatives to the user as well as improvements in the manufacture of reclosable bags. An improvement would be to use a material on a portion of the wall of the reclosable bag in alignment with the zipper. The material would have physical characteristics dissimilar to the film used to form the outer walls of the reclosable bag. The portion of material could be a flattened surface or in the form of the vertical ridges of the Ausnit reference, or any other protruding surfaces known to those skilled in the art.
Similar to the vertical ridges of the Ausnit reference or to the reinforcing ridge of the Tilman reference, the dissimilar material aligned with the zipper would facilitate locating the zipper by enhancing the tactile feel to the user in relation to the outer wall of the bag. Additionally, the use of dissimilar material would provide flexibility in the manufacture of reclosable bags by providing alternatives for positioning the zipper element in relation to the ease of locating the zipper by the user.